Press brakes are used to bend and otherwise deform metal objects such as metal pipes, tubes, bars, sheets, and plates. Press brakes conventionally possess a stationary metal bar and a parallel, translating bar adapted to move forcefully toward and away from the stationary bar. In order to move the translatable bar toward the stationary bar with sufficient force to deform metal disposed between the bars, one or more hydraulic rams are used to move the translatable bar. It is difficult to move the translatable bar evenly toward the stationary bar when the metal object to be deformed is disposed toward one end of the bars, since the degree of resistance would vary along the length of the translatable bar. Even though the force along the translatable bar might be uniform, when an opposing force of resistance varies along the length of the translatable bar, the translatable bar tends to tilt (i.e., become nonparallel) with respect to the stationary bar. The degree of tilt is difficult to predict and causes the metal object to be deformed in unpredictable, undesirable ways.
Various systems have been designed to try to maintain the translating bar in a parallel relation with the stationary bar, regardless of any variation in resistance along the length of the translatable bar. Such systems usually include sensors, hydraulic flow dividers, and metering devices adapted to modify the force applied along the length of the translatable bar to counteract the variation in resistance along the translatable bar. Most of these systems are complex and expensive and often still do not maintain the desired parallel relation of the two bars.